State migration in multiple NIC RDMA enabled devices

Abstract

A method is provided for transferring control between a first network interface and at least a second network interface in a same multiple network interface device after the first network interface transmits an identifier generated by the first network interface. The method includes receiving a message from the second network interface to a program component, the message indicating the reception of the identifier from a second device. Next, the method provides for querying the first network interface to supply the program component with a list of identifiers generated by the first network interface and associated memory locations in the multiple network interface device memory. If the identifier received by the second device is present in the list, the method provides for transmitting a memory location associated with the identifier to the second network interface.

Description

FIELD OF THE INVENTION[0001]This invention relates generally to networking and, more particularly, relates to more efficiently use of CPU resources in a networked devices.BACKGROUND OF THE INVENTION[0002]Networked computing has become almost ubiquitous. Many computers in use today have multiple network interface controllers, or NICs. The speed of the data transfers allowed by these NICs has grown faster than the CPU processing power and memory system bandwidth available to process this data. Consequently, more of this processing has been moved into the NIC card themselves. While this solution works to a point, additional standards activities have been underway to develop protocols which further assist in offloading the burden of network processing from the CPU and memory bus to the NIC.[0003]One such protocol is remote direct memory access or RDMA. RDMA is a protocol which allows the NIC card to place a data packet in a predetermined memory location in the computer systems main memo...

AI Technical Summary

Benefits of technology

[0007]Embodiments are directed to methods that overcome the problem of a STag arriving at a network interface that did not generate the STag. The method relies on network interfaces on a given computer having unique STags. This can be assured by the operating system. Because STags on a given computer are unique, a network interface receiving an STag generated by another network interface on the same computer is enabled to detect that the STag was generated by a different network interface. When such a STag is detected, the network interface receiving the STag passes this STag to a higher level of software, which can be an RDMA program component which resides in the OS kernel. The RDMA program component can identify which NETWORK INTERFACE generated the STag and query the associated network interface for all STags generated by this network interface and the associated addresses of the allocated memory. The address is then passed to the network interface that received the unknown STag. With the memory address, the network interface can then complete the data transfer.

Problems solved by technology

This can cause difficulty for a machine with multiple NICs when performing an RDMA transfer.

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